A conventional charged particle beam system in which a plurality of particle beamlets is directed onto an object is known from WO 2005/024881. The system is an electron microscope in which a plurality of primary electron beamlets are focused in parallel to form an array of primary electron beam spots on the object. Secondary electrons generated by the primary electrons and emanating from respective primary electron beam spots are received by a charged particle imaging optics to form a corresponding array of secondary electron beamlets which are supplied to an electron detection system having an array of detection elements such that each secondary electron beamlet is incident on a separate detection element. Detection signals generated from the detection elements are indicative of properties of the object at those locations where the primary electron beam spots are formed.
By scanning the array of primary electron beam spots across the object surface, it is possible to obtain an electron microscopic image of the object. It is desirable to obtain images at a high resolution and a high throughput. For this purpose it is desirable to achieve small primary electron beam spots on the object and to be able to scan the primary electron beam spots rapidly across the object surface.
Additional prior art is disclosed in U.S. Pat. No. 7,960,697 B2.